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SODA RFC

This document will act as RFC centre for the SODA http://www.ivoa.net/documents/SODA/index.html .

Review period: 12th October to 24th November 2016

In order to add a comment to the document, please edit this page and add your comment to the list below in the format used for the example (include your WikiName so authors can contact you for further information). When the author(s) of the document have considered the comment, they will provide a response after the comment.

Discussion about any of the comments or responses should be conducted on the DAL WG mailing list, dal@ivoa.net . However, please be sure to enter your initial comments here for full consideration in any future revisions of this document.

Implementations

Links and description of existing interoperable implementations

++ SODA sync service

resourceIdentifier : ivo://cadc.nrc.ca/soda#sync

standardID : ivo://ivoa.net/std/SODA#sync-1.0

accessURL : http://www.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/caom2ops/sync

++ SODA async

resourceIdentifier : ivo://cadc.nrc.ca/soda#async

standardID ivo://ivoa.net/std/SODA#async-1.0

accessURL http://www.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/caom2ops/async"

  • GAVO SODA half client and ... server
see : http://mail.ivoa.net/pipermail/dal/2016-March/007414.html

  • CASDA home page. Restricted access
https://casda.csiro.au/casda_data_access/

  • CASDA validator
https://github.com/csiro-rds/sodalint

Comments from the Community


  • Sample comment (by BrunoRino): ...
    • Response (by authorname): ...

Comments from Pierre Fernique


1) This document is clearly technical and requires the knowledge of several other IVOA documents. The section 4 is a great help to understand the associated relations. But the addition of a dedicated schema showing the SODA interactions with the other IVOA protocols directly connected to SODA (TAP, SIAv2, DATALINK) just after the general usual global IVOA protocol schema could help a little bit more.
This diagram exists in SIAV2.0 We could repeat it or refer to it. Only drawback is that this diagram still uses "AccessData" name instead of SODA. Maybe an erratum is necessary -- FrancoisBonnarel - 2016-11-30
2) Document factoring suggestions:
- The usage of very small subsections (page 6 and follows) describing usecases could be refactored in a list of items and sub-items.
- The multiple repetition of bibliographic reference should be avoid (ex: page 12)
Your two suggestion have been integrated. thanks -- FrancoisBonnarel - 2016-11-30
3) Coherence:
- Some utype uses domain prefix (obscore:) and some others forget de domain prefix (exemple page 15 3.2.7)
- The font for Obscore label is not always homogeneized (ex: 4.3 "content-type", "access_format", "access_url").
The two suggestions have been integrated -- FrancoisBonnarel - 2016-11-30
4) Missing definition:
- The three-Factor semantic should be described a little bit more. It is difficult to see the relation with the way to express the parameter (page 15)
- The "resourceIdentifier" parameter is not described in the document => "If the service is registered, the provider can include a resourceIdentifier parameter" (page 18)
The resourceIdentifier is needed in the case the service is known in the registry. Text has been completed -- FrancoisBonnarel - 2016-11-30
7) Questions/suggestions:
- It appears quite strange to express a MAX value for structured objects (CIRCLE, POLYGON, ...) thanks to the VOTable VALUES element. What MAX mean in such case ? I suppose that the idea is to provide the limit of the query region. In the text, it is said that it should be taken as a suggested values. I am a quite uncomfortable with this VOTable usage.
This part has been strongly modified. Reasons for using MAX for the "englobing" area in the case of CIRCLE and POLYGON has been clarified and the englobing MAX feature has been removed for BAND and TIME (xtype=interval). Nothing more can be done before we have a better way to link PARAMETERS to datamodel structures. -- FrancoisBonnarel - 2016-11-30

- May be, emphasis the fact that the HTTP error code must be properly set (4xx or 5xx)
- Page 22, it is said: "For example, if an {async} job included two CIRCLE and two BAND values, there must be four results" => is it really reasonable to let open this possibility difficult to understand/manage both for the client and the server ? I see this sentence more as an illustration of the lack of boolean constraints on multiple parameters. I would suggest to adopt the AND implicit rule rather to provide all the possible combinations
Humm multiple PARAMETERS is only optional. (see the section above on "Error messages". In case services really want to implement this I don't think they want "AND" -- FrancoisBonnarel - 2016-11-30


8 ) Typos:
p5 - "SODA servces" => "i" missing
p5 - 1.1.2 "descibed" => described
p13 - "of ther data" -> remove "r"
p13 - "SODA Filtering" => F should be in lowercase
p15 - 3.2.7 => simple quote => double quote (utype 'obscore...)
p16 ""Wthin" => "Within"
p16 ""servces" => "services"
page 17 "descrbes" => "describes"
page 18 - "obs_puclishder_did" => "obs_publisher_did"
page 18 - "obs_publishder_did" -> "obs_publisher_did"
page 19 "data-" => "data"
page 22 "nomative" => "normative"
page 22 - "re-organised" => "R" uppercase
page 22 - "patameters" => "parameters"

Typos fixed. thanks. -- FrancoisBonnarel - 2016-11-30

-- PierreFernique - 2016-10-20

Comments from Markus Demleitner

(1) p.8, "The considerations on naming the resource given in sect. 2.1 apply for it." -- "apply to it"? "apply here as well"?

"here as well" looks fine. Fix made -- FrancoisBonnarel - 2016-11-30

(2) p. 10/11 "The values for the ID parameter are generally discovered from data discovery or DataLink requests" -- since DataLink in general does not allow data discovery, I think the "or DataLink" should be deleted here. Even if a Datalink step is between the discovery and the SODA operation (as I believe it will generally be), the data id itself is a product of the discovery phase.

Fix has been made -- FrancoisBonnarel - 2016-11-30

(3) I am uncertain what the purpose of sect. 3.2.7 is, in particular at this point in the document structure (next to the special parameter definitions). If it absolutely must stay in, it should at least be better placed within the document structure, at least as a subsection of its won, or perhaps as an appendix, also adding an indication as to who is the adressee of this information. Or perhaps that's material for an implemenation note in the first place?

This has been transformed in a subsection. this statement is as important as the three factor semantics for understanding of what it's going on with SODA -- FrancoisBonnarel - 2016-11-30

(4) What is supposed to happen if someone specifies both CIRCLE and POLYGON, and perhaps POS on top? (my take: it's an error; in my implementation, spatial axes can additionally be constrained by axes-specific keys (RA, PIXEL_1, etc), and there's no way any other semantics could ever be sanely implemented.

(5) 3.2.3 still mentions the region xtype that I think was/will be dropped in DALI; if that's the case it should go here as well (also in the interest of not clobbering future developments in which that xtype might be used for something more principled).

This has been removed -- FrancoisBonnarel - 2016-11-30

(6) 3.2.4 talks about "energy interval(s)", which, while not factually incorrect, is misleading since we are actually specifying is wavelength intervals, so I think we should say that.

Fixed. -- FrancoisBonnarel - 2016-11-30

(7) 3.2.4 also says "barycentric wavelength in meters"; I'm not sure that's not too constraining, but perhaps using topocenter rather than barycenter if that's what your data has wouldn't matter too much. But if we go into this trouble, I'd say we also have to say "This specification does not constrain whether vacuum wavelengths or air wavelengths are given". Choosing either one would alienate certain communities. Next time we do a VO, let's agree to use frequency or energy to constrain the spectral axis, and we won't have that problem.

(8) In the opening paragraphs of sect. 4, there is "This mechanism is expected to be the primary means of finding and using a SODA service." Since it is not quite clear what this refers to and doesn't add normative value, I suggest this should be taken out.

Not done. primary means is opposed to discovery via the registry -- FrancoisBonnarel - 2016-11-30

(9) In the example in the opening material to sect. 4, there are no DESCRIPTION elements to the PARAMs, which I think sets a bad example. Can't we just add some? Or at least say that "\xmlel{DESCRIPTION} elements, while highly recommended in practice, have been left out in this example for brevity"?

This has been fixed -- FrancoisBonnarel - 2016-11-30 -- MarkusDemleitner - 2016-11-23

Comments from TCG members during the TCG Review Period: 2016-10-12 to 2016-11-24

WG chairs or vice chairs must read the Document, provide comments if any and formally indicate if they approve or do not approve of the Standard.

IG chairs or vice chairs are also encouraged to do the same, although their inputs are not compulsory.

TCG Chair & Vice Chair ( _Matthew Graham, Pat Dowler )

Applications Working Group ( _Pierre Fernique, Tom Donaldson )

Data Access Layer Working Group ( François Bonnarel, Marco Molinaro )

Data Model Working Group ( _Mark Cresitello-Dittmar, Laurent Michel )

Grid & Web Services Working Group ( Brian Major, Giuliano Taffoni )

Registry Working Group ( _Markus Demleitner, Theresa Dower )

Though this may be odd coming from Registry, and though I'm usually totally in favour of standards regulating their Registry aspects, in this particular case my feeling is that the standard has very little relationship to the Registry, and it would benefit from removing most of the references to it. This would mean:

(1) p.5, "First, a SODA service could be found in the IVOA Registry and used directly." -- since it is impossible to know a dataset identifier (or the parameters supported by a SODA service) in this scenario, and even if (e.g., from an examples document) you had that it's hard to imagine what useful purpose could be served by such a thing, I think this sentence should be taken out.

(2) p.5, "Since the discovery of SODA services ... make use of a registry extension" -- I'd strike that sentence, too. The consequence implied here is tenuous at best (parameters are actually declared within the interface, whereas capability metadata will typically cover things that aren't in the Datalink descriptor), and we don't have to apologise for not defining a registry extension anyway. This also lets us drop 1.1.1, together with the "see also" to 4.1, which in turns largely repeats 1.1.1 only adding that it "is not expected to be a common usage pattern". So, 4.1 could go, too.

Since the sections are not wrong as such, I'm not insisting, but the document certainly would be shorter and clearer without them.

Actually, I can see two use cases for having SODA services registred:

(a) Users might at some point search for "resources with associated SODA service"; the scenario here could be that a user has located a service but wants a SODA-enabled version of it. How likely that is I can't say.

(b) Infrastructure might look for SODA services to validate. Together with an examples page that might even be possible.

In both cases I think the story isn't terribly strong, so I'm not suggesting even mentioning either in the document.

Having said that, Registry approves.

Oh, and we've also put SODA.vor into the repo. That's a StandardsRegExt record for SODA. When you go to REC, please update the date and submit it to the RofR as described in WriteAStandardsRecord.

-- MarkusDemleitner - 2016-11-23

Semantics Working Group ( _Mireille Louys, Alberto Accomazzi )

Education Interest Group ( _Massimo Ramella, Sudhanshu Barway )

Time Domain Interest Group ( _John Swinbank, Dave Morris )

Data Curation & Preservation Interest Group ( Françoise Genova )

Operations Interest Group ( _Tom McGlynn, Mark Taylor )

Knowledge Discovery Interest Group ( Kaï Polsterer )

Theory Interest Group ( _Carlos Rodrigo )

Standards and Processes Committee ( Françoise Genova)


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